Weird, because I asked about the Mac Mini for my mother-in-law, and the guy tried to convince me that I need to buy the 1TB version because she'll fill the 500GB up with photo's. I wanted to call him a moron but figured I wouldn't embarrass the wife, so I walked off and let him talk to her about it.
LOL!!!! (I also suppose he has never heard of external drives.)
I was paring down the crud lately on my iMac. Unused cache files (quite a few caches and big caches at that) and other stuff not needed at the moment. I have a LOT left over that I thought would be a good idea to hold onto: like multiple versions of an opensim server, the source code for a pretty large project, and n versions of the executable builds from that project.
The result: under 600 GB.
My current drive is 3/4 of a TB. I plan on starting with Apple's data drive and a 512 GB SSD (with wear leveling that leaves plenty of space for new writes). When I need more space I will just stick in another drive or upgrade the data drive.